Rapid life-history diversification of an introduced fish species across a localized thermal gradient.

Fengyue Zhu,Tanglin Zhang,Jianfeng Tang,Jing Yuan,Zhiqiang Guo,Brian R Murphy,Jiashou Liu,Andrew L Rypel,Zhongjie Li,Michael Sears

doi:10.1371/journal.pone.0088033

Abstract

Climatic variations are known to engender life-history diversification of species and populations at large spatial scales. However, the extent to which microgeographic variations in climate (e.g., those occurring within a single large ecosystem) can also drive life-history divergence is generally poorly documented. We exploited a spatial gradient in water temperatures at three sites across a large montane lake in southwest China (Lake Erhai) to examine the extent to which life histories of a short-lived fish species (icefish, Neosalanx taihuensis) diversified in response to thermal regime following introduction 25 y prior. In general, warmwater icefish variants grew faster, had larger adult body size and higher condition and fecundity, but matured at smaller sizes. Conversely, coldwater variants had smaller adult body size and lower condition, but matured at larger sizes and had larger eggs. These life-history differences strongly suggest that key ecological trade-offs exist for icefish populations exposed to different thermal regimes, and these trade-offs have driven relatively rapid diversification in the life histories of icefish within Lake Erhai. Results are surprisingly concordant with current knowledge on life-history evolution at macroecological scales, and suggest that improved conservation management might be possible by focusing on patterns operating at microgeographical, including, within-ecosystem scales.

Highlights

Biologists have long been fascinated with how thermal habitat variations shape species evolution and life histories [1,2,3,4]
Across all months and sites, a total of 5400 individual icefish were sampled from Lake Erhai
Mean total lengths and weights were highest in the warmwater northern icefish variants followed by mid-lake icefish and cold water southern icefish (Fig. 2 A, B)

Summary

Introduction

Biologists have long been fascinated with how thermal habitat variations shape species evolution and life histories [1,2,3,4]. Ecologists have explored diverse ecogeographic and macroecological hypotheses on how temperature affects populations and ecosystems by producing life-history variants [6,7,8]. The macroecology literature is replete with examples of how large-scale variations in temperature and climate (e.g., as occurs across a continent) drive the development and maintenance of species and populations [9,10,11,12,13]. Less is known on how microgeographic or meso-scale variations in temperature encourage life-history diversification, even though climate often varies dramatically at these spatial scales as well [14,15]

Methods

Results

Conclusion